As diseases emerge and infections re-emerge, new and improved vaccines are needed. The decisions about which vaccines should be developed first can affect millions of people's health, quality of life, and economic progress. A new early-stage prototype software tool created by the Institute of Medicine -- the Strategic Multi-Attribute Ranking Tool (SMART) Vaccines 1.0 -- allows those involved in vaccine formation and delivery to prioritize the vaccines most urgently needed in the United States and other countries. The free software, its corresponding report, Ranking Vaccines: A Prioritization Software Tool, and a video tutorial are all available at http://www.nap.edu/smartvaccines/.